Journal of Visualization

, Volume 12, Issue 1, pp 17–25 | Cite as

Effect of rounded edged dimple arrays on the boundary layer development

  • Mitsudharmadi H. 
  • Tay C. M. J 
  • Tsai H. M 
Regular Paper

Abstract

The effect of a turbulent boundary layer subjected to a series of rounded edged shallow dimple arrays with dimple depth ratios, d/D of 4%, 8% and 12% were experimentally studied. Measurements show the existence of a higher flow speed region at the center of each dimple. The spanwise distribution of the mean wall shear stress immediately downstream of the centers of the last row of dimples does not vary with dimple depth, and is about 45% over that without the dimple array. Turbulence measurements and surface flow visualization shows that the flow over the shallowest dimple differs from the deeper dimples. Flow separation observed with the deeper rounded edged dimples produce similar flow structures as those from sharp edged dimples reported in the literature. However flow separation is not observed when d/D=4% but instead two other higher speed regions either side accompany the central flow. The effects of the dimples are rapidly suppressed by the flat surfaces between of the dimples, and the flow rapidly reverts back to an unmanipulated flat boundary layer flow in these areas.

Keywords

shallow dimple smooth edge dimple flow control wall shear stress turbulent flow 

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References

  1. Bakchinov, A. A., Grek, G. R., Klingmann, B. G. B., and Kozlov, V. V., “Transition experiments in a boundary-layer with embedded streamwise vortices,” Phys. Fluids, 7 (4), 820 (1995).CrossRefGoogle Scholar
  2. Ersoy, S., and Walker, J. D. a., “Viscous flow induced by counter-rotating vortices”, Phys. Fluids 28 (9), 2687–2698 (1985).MATHCrossRefGoogle Scholar
  3. Isaev, S. A., Leontiev A. I., and Baranov P. A., “Identification of self organized vortex-like structures in numerically simulated turbulent flow of a viscous incompressible liquid streaming around a dimple on a plane. Technical Phys. Lett., 26, 15–18 (2000).CrossRefGoogle Scholar
  4. Isaev, S. A., Leontiev A. I., Kudryavtsev N. A., Pyshnyi I. A., “The Effect of Rearrangement of the Vortex Structure on Heat Transfer under Condition of Increasing Depth of a Spherical Dimple on the Wall of a Narrow Channel,” High Temperature, 41, N2, 229–232. (2003)CrossRefGoogle Scholar
  5. Ligrani, P. M., “Flow visualization and flow tracking as applied to turbine components in gas turbine engines,” Measurement Science and Technology 11, 992–1006 (2000).CrossRefGoogle Scholar
  6. Ligrani, P. M., Harrison, J. L., Mahmood, G. I., and Hill, M. L., “Flow structure due to dimple depression on a channel surface,” Phys. Fluids 13 (11), 3442–3451 (2001).CrossRefGoogle Scholar
  7. Ligrani, P. M., Burgess, N. K., and Won, S. Y., “Nusselt numbers and flow structure on and above a shallow dimpled surface within a channel including effects of inlet turbulence intensity level,” J. Turbomachinery, 127, 321–329 (2005).CrossRefGoogle Scholar
  8. Mahmood, G. I., and Ligrani, P. M., “Heat transfer in a dimpled channel: combined influences of aspect ratio, temperature ratio, Reynolds number, and flow structure,” Int. J. Heat and Mass Transfer 45, 2011–2020 (2002).CrossRefGoogle Scholar
  9. Mitsudharmadi, H., Winoto, S. H., and Shah, D. A., “Development of most amplified wavelength Görtler vortices”, Phys. Fluids, 18, 014101 (2006).CrossRefGoogle Scholar
  10. Neuendorf, R., and Wygnanski, I., “On a turbulent jet flowing over a circular cylinder,” J. Fluid Mech. 381, 1–25 (1999).MATHCrossRefMathSciNetGoogle Scholar
  11. Won, S.Y., Zhang, Q., and Ligrani, P. M., “Comparisons of flow structure above dimpled surfaces with different dimple depths in a channel,” Phys. Fluids 17, 045105 (2005).CrossRefGoogle Scholar
  12. Yamagishi, Y., and Oki, M., “Numerical simulation of flow around a circular cylinder with curved sectional grooves,” Journal of Visualization 10 (2), 179–186 (2007).CrossRefGoogle Scholar

Copyright information

© The Visualization Society of Japan 2009

Authors and Affiliations

  • Mitsudharmadi H. 
    • 1
  • Tay C. M. J 
  • Tsai H. M 
  1. 1.Temasek LaboratoriesNational University of SingaporeSingapore

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